The following are links to helpful resources for the game. Please feel free to post/add to the list.
CR Converter - link to CR Converter to use during times of war. Requires registration. May need to find another converter due to the changes in version 0.3.2. Will revisit as needed.
WikkIkariam - great resource for ships, buildings and more.
Ikariam Boards - message boards for Ikariam with lots of useful info.
Ikariam Library - Another great site for tools and guides.
Ikariam Troop Calculator - Can be used for planning and tracking military expansion and the reduction of your enemies' military. The calculator will determine the gold price and resource cost of the units, their assault and defense values, and generate an estimate of military score the units represent.